1. Technical Field
The present invention relates to housing parts with sealing surfaces, such as covers or caps, which are fastened with a seal and fastening elements which engage through corresponding fastening openings on the housing parts or on other machine parts, in particular for internal combustion engines. In particular, the present invention concerns housing parts in which sleeves are provided in the fastening openings, which sleeves project in the direction of the sealing surface and which serve as pressure limiters for a seal. The present invention likewise concerns a seal for such a housing part.
Seals with plastic supporting frames which are provided with metallic inserts are already known. These inlets are usually metal elements such as, for example, metal discs, U-tongues or flanges, which are integrated in the region of the screw and serve there as pressure limiters, because the greatest forces are introduced at the screwing points. These pressure limiters are intended to prevent for example an elastomer seal from being compressed too strongly in the region of the fastening screws and hence losing its sealing effect. Seals are likewise known in which metal elements are used as path limiters or pressure limiters at other locations than the fastening passages. The forces of the fastening screws are only partially transferred here via the seal.
All the known solutions aim for a certain functional separation, in which other elements can support or receive a portion of the screwing forces, because the plastic support of the seal is not able to do this over a lengthy period of time, because its plastic can withdraw from a load by creeping away. The known plastic support therefore substantially has the function of supporting the seal, whilst metal elements which are integrated in the plastic support receive the screwing forces. It is likewise possible that a metallic supporting frame undertakes both functions.
Seals with metallic supporting frames of, for example, steel or aluminium, are becoming increasingly more expensive due, inter alia, to rising metal prices. Their replacement by plastic supporting frames can offer cost advantages particularly in the case of high production quantities. The present invention substantially concerns seals which consist of a punched-out supporting frame on which a seal body of elastomer material is vulcanized, and housing parts which can be connected with such seals.
2. Related Art
The fundamental aim is therefore to substitute the supporting frame of aluminium or steel by plastic. The problem exists here that plastic supporting frames, compared with metal supporting frames under operating conditions (screwing forces, temperature, time) do not have a sufficient strength and therefore the screwing security is no longer guaranteed. One method which is already applied in seals with plastic supporting frames consists in integrating metallic elements into the supporting frame. These largely receive the screwing forces and prevent a “creeping away” of the plastic under stress (pressure, temperature, . . . ). As these additional elements also, in turn, entail costs, a solution is to be found in which the integration of inserts can be dispensed with.
In addition, it is to be possible to also make such a seal resistant to temperature, oil, vibration and corrosion, in order to also be able to be used in machine covers such as, for example, cylinder head covers and oil sumps of plastic.